To cut trees it is known to use cutting machines mounted on tractors and incorporating hydraulically operated shears the legs of which cut through the tree trunk. This cutting method gives extensive damage on the tree trunk. To avoid such damage, the use of chain saws has been suggested, the chain saws being mounted on the tractor in a manner permitting the guide bars to move towards another in a horizontal plane. Hitherto known machines of this kind suffer, however, from two considerable disadvantages, via, the readiness of the chain saws to become stuck in the kerf whereby not only the chains are damaged or torn away but in addition the guide bars are bent in the attempts to remove the saw from the tree, and also the difficulty in sawing through the entire tree as it is not possible to make the two saw chains run closely adjacent one another in the tree centre.